The present invention relates to lumber processing sawmill equipment, and more particularly to an automated planer machine.
Planing machines are used in the lumber industry to profile the four sides of a piece of lumber according to desired dimensions.
The usual main components of a planing machine comprise a feed table, upper and lower planing heads (also called cylinders), a linebar, and right and left side planing heads. The feed table is used for vertical positioning of the piece of lumber with respect to the upper and lower planing heads. The upper and lower planing heads are vertically adjustable and are used to respectively plane the top and bottom surfaces of the piece of lumber. The linebar is usually fixed and is used to laterally guide the piece of lumber along a traveling course in the planing machine. The right and left side planing heads are laterally adjustable and are used to respectively plane the right and left surfaces of the piece of lumber.
A supply table upstream from the planing machine is normally used to position the piece of lumber and forward it at a high speed toward the planing machine. The piece is picked-up vertically by the feed table and sideways by the fixed linebar. The four side surfaces of the piece of lumber are profiled by the planing heads. The vertical and lateral positions of the planing heads are adjusted to obtain the desired dimensions. The pieces of lumber, to be admissible on the market, must meet certain standards determining the finishing dimensioning and quality of the surfaces. The pieces, after the planing process, are graded depending on the obtained results and the retail price is set as a function of these results. Many pieces will be downgraded (this term is used to identify a piece presenting defects and whose retail price will be reduced proportionally to its state) because they present some wane. Wane defines a machining defect due to a lack of material during the profiling of the piece. When the position of the feed table is too high, the piece of lumber passes above the lower planing head without the planing head being able to take some material off. This phenomenon is called bottom waning. Likewise, when the feed table is too low, the piece of lumber passes below the upper planing head without the planing head being able to pick material off, causing top waning. It is the same for the side planing heads where left or right waning may happen.
Waning defects are problems frequently encountered in a planing machine. A piece of lumber presenting some wane looses a part of its value and thus represents important financial losses for planing mills.
In conventional planing machines, the position adjustments of the planing heads and the feed table are achieved manually. The adjustments take a lot of time and their accuracy is hard to reach because only a few reference points are available. Precision rulers or other measuring instruments that may facilitate this laborious operation are used. Down times are numerous and long: correction of wane, size settings, production changes (other sizes) and unjamming operations to remove a piece broken or jammed in the planing machine. The financial losses due to down times of the planing machine become soon astronomic.
An object of the present invention is to provide a planing machine having an automated positioning system for improved performance over the planing machines of the prior art.
Another object of the invention is to provide a planing machine capable of achieving piece by piece optimization.
Another object of the present invention is to provide a planing machine having a design which facilitates access to the planing heads and some other parts, improves the visibility, and facilitates unjamming or repair operations if necessary.
Another object of the present invention is to provide a planing machine having certain parts having improved design and construction for high rate production.
Another object of the present invention is to provide a planing machine having planing heads which can be repositioned during operation.
According to the present invention, there is provided an automated planer machine for planing a piece of lumber having top, side and bottom surfaces, comprising:
a feed table adapted to slidably receive the bottom surface of the piece of lumber along a traveling course;
at least one planing head extending on a side of the planing course and adapted to plane one of the surfaces of the piece of lumber;
a linebar projecting on a side of the feed table and adapted to slidably receive one of the side surfaces of the piece of lumber;
feed rolls extending along the traveling course and adapted to move the piece of lumber along the traveling course;
positioning means responsive to respective control signals for adjusting a height of the feed table and a planing level of said at least one planing head with respect to said one of the surfaces of the piece of lumber according to the control signals; and
position encoders respectively coupled to the feed table and said at least one planing head, for producing positional signals indicative of the height of the feed table and the planing level of said at least one planing head.